1. Technical Field
This application generally relates to a data storage system, and more particularly to techniques used with device initialization.
2. Description of Related Art
Computer systems may include different resources used by one or more host processors. Resources and host processors in a computer system may be interconnected by one or more communication connections. These resources may include, for example, data storage devices such as those included in the data storage systems manufactured by EMC Corporation. These data storage systems may be coupled to one or more host processors and provide storage services to each host processor. Multiple data storage systems from one or more different vendors may be connected and may provide common data storage for one or more host processors in a computer system.
A host processor may perform a variety of data processing tasks and operations using the data storage system. For example, a host processor may perform basic system I/O operations in connection with data requests, such as data read and write operations.
Host processor systems may store and retrieve data using a storage device containing a plurality of host interface units, disk drives, and disk interface units. Such storage devices are provided, for example, by EMC Corporation of Hopkinton, Mass. and disclosed in U.S. Pat. No. 5,206,939 to Yanai et al., U.S. Pat. No. 5,778,394 to Galtzur et al., U.S. Pat. No. 5,845,147 to Vishlitzky et al., and U.S. Pat. No. 5,857,208 to Ofek. The host systems access the storage device through a plurality of channels provided therewith. Host systems provide data and access control information through the channels to the storage device and storage device provides data to the host systems also through the channels. The host systems do not address the disk drives of the storage device directly, but rather, access what appears to the host systems as a plurality of logical disk units. The logical disk units may or may not correspond to the actual disk drives. Allowing multiple host systems to access the single storage device unit allows the host systems to share data stored therein.
Different tasks may be performed in connection with devices of a data storage system. One task that may be performed in connection with a device of a data storage system is initialization or formatting of the device. One existing technique for initializing or formatting a device on a data storage system may include, in addition to other processing steps, initializing each track of the device such as with an initialization pattern.
The foregoing existing technique has some drawbacks. Initializing each track of the device may be very time consuming and use a lot of computing resources. A track may correspond to a portion of a physical storage such as, for example, multiple blocks on a data storage device. In connection with initializing each track on the device with an initialization pattern, the resources of the data storage system may be consumed to saturation so that the service time to process other requests such as, for example, host I/O operations, may be unacceptable. Additionally, the amount of time to perform the initialization prior to the device being available for use may also be unacceptable particularly as the capacity of devices and data storage systems increase.
The initialization may be performed in connection with different operations and commands. Initialization may be performed in connection with an application determining that a device should be initialized. For example, a snapshot application may be used in connection with making a snapshot or point in time copy of data from a first device to a second device. While the snapshot of data is in the process of being copied to the second device, a read operation to access data on the second device may be redirected to use a copy of data on the first device if the data has not yet been copied from the first device to the second device. If a snapshot application session is terminated prior to completion of making the snapshot on the second device, the snapshot application may set an indicator indicating that the second device requires initialization due to the incomplete and aborted snapshot operation.
Thus, it may be desirable to utilize a technique in connection with device initialization which efficiently utilizes resources of a data storage system and reduces the amount of time before the device is available for use. It may also be desirable that the technique be scalable as data storage capacity of the data storage system and devices therein increases.